logs of streaming replication

Hi,

There was streaming replication is configured between 2 servers and
was running fine since so long, but now I found that streaming
replication is broken.

I used below command:

select * from pg_stat_replication;

but there is no output anymore.

So I just wanted to check the logs of streaming replication, so that I
can troubleshoot the cause.

So please help me.

Regards,
Atul